1. Field of the Invention
This invention relates generally to electrostatic coating apparatus and methods, and more particularly to a disk for an electrostatic coating powder distributor.
2. Description of the Prior Art
The most pertinent prior art patent of which we are aware is represented by a U.S. Pat. No. 3,843,054 issued Oct. 22, 1974 and which discloses an electrostatic powder spraying apparatus. In that apparatus, there is a non-rotating disk at the outlet of a powder conveying conduit. An electrostatic field is established between the edge of the disk and the articles to be coated. As powder is delivered radially outward from the disk, the particles of powder are electrically charged at the disk and move through the electrostatic field toward the articles to be coated, which are usually at ground potential and, being differently charged from the particles, thereby attract the particles.
A difficulty encountered heretofore with such apparatus is irregularity of coating of the articles. We have endeavored to determine the cause of such irregularities and have determined that an accumulation of particles on the upper surface of the disk occurs during operation. Occasionally, clumps or globs of such particles become dislodged from the disk and move through the field to the articles to be coated, resulting in irregular coating where such clumps become deposited. The present invention is addressed to solving this problem.